ProgramNode(0...14)(
  [],
  StatementsNode(0...14)(
    [InterpolatedStringNode(0...9)(
       (0...1),
       [StringNode(1...4)(nil, (1...4), nil, "a\n"),
        EmbeddedStatementsNode(4...8)((4...6), nil, (7...8))],
       (8...9)
     ),
     TrueNode(10...14)()]
  )
)
